Critical tissue zinc concentration: a method to diagnose zinc status in chickpea and lentil

An experiment was conducted using zinc (Zn) deficient sandy loam soil to study the effect of Zn nutrition on biomass accumulation in chickpea (Cicer arietinum L.) and lentil (Lens esculentus L.) and to determine the critical tissue Zn concentration at different growth stages for plant diagnostics. Different levels of Zn (0, 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0, 30.0, 50.0 μg Zn g−1 soil) created in soil by adding ZnSO4. Tissue Zn concentration was moderate to highly correlated with dry matter production in chickpea (r2 = 0.564–0.879) and lentil (r2 = 0.445–0.864) up to 60 days after sowing. Based on quadratic relationship with dry matter production, the critical concentration of tissue Zn varied from 38.0 to 44.3 μg g−1 for chickpea and 30.6 to 64.5 μg g−1 for lentil. Considerable variation was observed in critical Zn concentration with leaf age in chickpea and lentil. Young fully expanded leaf of chickpea and mature leaf of lentil was found to be the effective sampling organ for diagnosing Zn status of these crops.